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<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="boost_test.usage_variants"></a><a class="link" href="usage_variants.html" title="Usage variants">Usage variants</a>
</h2></div></div></div>
<p>
      The <span class="emphasis"><em>Unit Test Framework</em></span> supports three different usage
      variants:
    </p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
          <a class="link" href="usage_variants.html#boost_test.usage_variants.single_header">The header-only
          variant</a>
        </li>
<li class="listitem">
          <a class="link" href="usage_variants.html#boost_test.usage_variants.static_lib">The static library
          variant</a>
        </li>
<li class="listitem">
          <a class="link" href="usage_variants.html#boost_test.usage_variants.shared_lib">The shared library
          variant</a>
        </li>
</ol></div>
<p>
      In most cases you shouldn't have problems deciding which one to use, since
      there are clear reasons why would you prefer each one. Following sections should
      help you with the decision.
    </p>
<h4>
<a name="boost_test.usage_variants.h0"></a>
      <span class="phrase"><a name="boost_test.usage_variants.single_header"></a></span><a class="link" href="usage_variants.html#boost_test.usage_variants.single_header">Header-only
      usage variant</a>
    </h4>
<p>
      If you prefer to avoid the compilation of standalone library, you should use
      the header-only variant of the <span class="emphasis"><em>Unit Test Framework</em></span>. This
      variant only requires you to include the unique header: <code class="computeroutput"><span class="preprocessor">#include</span>
      <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">included</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code> and
      there is no need to link with any library. There are several ways to perform
      the initialization, but the simplest way is the following:
    </p>
<pre class="programlisting"><span class="preprocessor">#define</span> <a class="link" href="utf_reference/link_references/link_boost_test_module_macro.html" title="BOOST_TEST_MODULE"><code class="computeroutput"><span class="identifier">BOOST_TEST_MODULE</span></code></a> <span class="identifier">test</span> <span class="identifier">module</span> <span class="identifier">name</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">included</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span> <span class="comment">/* path is different than the other variants! */</span>
</pre>
<p>
      <a class="link" href="utf_reference/link_references/link_boost_test_module_macro.html" title="BOOST_TEST_MODULE"><code class="computeroutput"><span class="identifier">BOOST_TEST_MODULE</span></code></a> macro needs to be
      defined <span class="bold"><strong>before</strong></span> the include and should indicate
      the name of the test module. This name can include spaces and does not need
      to be wrapped in quotes.
    </p>
<p>
      <a class="link" href="adv_scenarios/single_header_customizations.html" title="Header-only variant customizations">This
      section</a> gives additional details on how to customize this usage variant.
      In particular, it is possible to have several compilation units with this variant,
      as explained in the section <a class="link" href="adv_scenarios/single_header_customizations/multiple_translation_units.html" title="Header-only with multiple translation units">Header-only
      with multiple translation units</a>.
    </p>
<h4>
<a name="boost_test.usage_variants.h1"></a>
      <span class="phrase"><a name="boost_test.usage_variants.static_lib"></a></span><a class="link" href="usage_variants.html#boost_test.usage_variants.static_lib">Static
      library usage variant</a>
    </h4>
<p>
      For most users, who has an access to pre-built static library <a href="#ftn.boost_test.usage_variants.f0" class="footnote" name="boost_test.usage_variants.f0"><sup class="footnote">[1]</sup></a> of the <span class="emphasis"><em>Unit Test Framework</em></span> or can <a class="link" href="adv_scenarios/build_utf.html" title="Building the Unit Test Framework">build
      it</a> themselves, following usage can be most versatile and simple approach.
      This usage variant entails two steps.
    </p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<p class="simpara">
          First, the following line needs to be added to all translation units in
          the test module:
        </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<p class="simpara">
          One and <span class="bold"><strong>only one</strong></span> translation unit should
          include following lines:
        </p>
<pre class="programlisting"><span class="preprocessor">#define</span> <a class="link" href="utf_reference/link_references/link_boost_test_module_macro.html" title="BOOST_TEST_MODULE"><code class="computeroutput"><span class="identifier">BOOST_TEST_MODULE</span></code></a> <span class="identifier">test</span> <span class="identifier">module</span> <span class="identifier">name</span>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<p class="simpara">
          <a class="link" href="utf_reference/link_references/link_boost_test_module_macro.html" title="BOOST_TEST_MODULE"><code class="computeroutput"><span class="identifier">BOOST_TEST_MODULE</span></code></a> macro needs
          to be defined <span class="bold"><strong>before</strong></span> the include and should
          indicate the name of the test module. This name can include spaces and
          does not need to be wrapped in quotes.
        </p>
</li>
<li class="listitem">
          The second step is to link with the <span class="emphasis"><em>Unit Test Framework</em></span>
          <span class="bold"><strong>static</strong></span> library.
        </li>
</ol></div>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
        Header <code class="computeroutput"><span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
        is an <span class="emphasis"><em>aggregate</em></span> header: it includes most of the other
        headers that contains the Unit Test Framework definitions.
      </p></td></tr>
</table></div>
<p>
      The flip side of this usage variant is that each test module following this
      usage variant is going to be statically linked with <span class="emphasis"><em>Unit Test Framework</em></span>,
      which might be something you want to avoid (to save space for example). For
      more information about these configuration options check <a class="link" href="adv_scenarios/static_lib_customizations.html" title="Static-library variant customizations">this
      section</a>.
    </p>
<h4>
<a name="boost_test.usage_variants.h2"></a>
      <span class="phrase"><a name="boost_test.usage_variants.shared_lib"></a></span><a class="link" href="usage_variants.html#boost_test.usage_variants.shared_lib">Shared
      library usage variant</a>
    </h4>
<p>
      In the project with large number of test modules the static library variant
      of the <span class="emphasis"><em>Unit Test Framework</em></span> may cause you to waste a lot
      of disk space. The solution is to link test module dynamically with the <span class="emphasis"><em>Unit
      Test Framework</em></span> built as a shared library. This usage variant entails
      two steps.
    </p>
<div class="orderedlist"><ol class="orderedlist" type="1">
<li class="listitem">
<p class="simpara">
          First you need to add following lines to all translation units in a test
          module:
        </p>
<pre class="programlisting"><span class="preprocessor">#define</span> <a class="link" href="utf_reference/link_references/link_boost_test_dyn_link.html" title="BOOST_TEST_DYN_LINK"><code class="computeroutput"><span class="identifier">BOOST_TEST_DYN_LINK</span></code></a>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<p class="simpara">
          and <span class="bold"><strong>only one</strong></span> translation unit should include
          following lines
        </p>
<pre class="programlisting"><span class="preprocessor">#define</span> <a class="link" href="utf_reference/link_references/link_boost_test_module_macro.html" title="BOOST_TEST_MODULE"><code class="computeroutput"><span class="identifier">BOOST_TEST_MODULE</span></code></a> <span class="identifier">test</span> <span class="identifier">module</span> <span class="identifier">name</span>
<span class="preprocessor">#define</span> <a class="link" href="utf_reference/link_references/link_boost_test_dyn_link.html" title="BOOST_TEST_DYN_LINK"><code class="computeroutput"><span class="identifier">BOOST_TEST_DYN_LINK</span></code></a>
<span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">test</span><span class="special">/</span><span class="identifier">unit_test</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
</pre>
<p class="simpara">
          <code class="computeroutput"><span class="identifier">BOOST_TEST_MODULE</span></code> and
          <code class="computeroutput"><span class="identifier">BOOST_TEST_DYN_LINK</span></code> macros
          needs to be defined <span class="bold"><strong>before</strong></span> the include.
          <code class="computeroutput"><span class="identifier">BOOST_TEST_MODULE</span></code> should
          be set to test module name. This name can include spaces and does not need
          to be wrapped in quotes.
        </p>
</li>
<li class="listitem">
          The second step is to link with the <span class="emphasis"><em>Unit Test Framework</em></span>
          <span class="bold"><strong>shared</strong></span> library.
        </li>
</ol></div>
<p>
      The flip side of this usage variant is that you will need to make sure the
      <span class="emphasis"><em>Unit Test Framework</em></span> shared library is accessible at runtime
      to a test module.
    </p>
<p>
      In addition shared library usage variant facilitates custom test runners. For
      more information about this check <a class="link" href="adv_scenarios/shared_lib_customizations.html" title="Shared-library variant customizations">this
      section</a>.
    </p>
<div class="caution"><table border="0" summary="Caution">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Caution]" src="../../../../../doc/src/images/caution.png"></td>
<th align="left">Caution</th>
</tr>
<tr><td align="left" valign="top"><p>
        On Windows, the test module and the <span class="emphasis"><em>Unit Test Framework</em></span>
        shared library should link to the same CRT. Not doing so (for instance <span class="emphasis"><em>Unit
        Test Framework</em></span> shared library in <span class="emphasis"><em>release</em></span>
        mode while the test module is in <span class="emphasis"><em>debug</em></span>) will lead to
        crashes.
      </p></td></tr>
</table></div>
<div class="footnotes">
<br><hr style="width:100; text-align:left;margin-left: 0">
<div id="ftn.boost_test.usage_variants.f0" class="footnote"><p><a href="#boost_test.usage_variants.f0" class="para"><sup class="para">[1] </sup></a>
        these files are distributed with the packaging systems on Linux and OSX for
        instance
      </p></div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2001-2022 Boost.Test contributors<p>
        Distributed under the Boost Software License, Version 1.0. (See accompanying
        file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div></td>
</tr></table>
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